/****************************************************************************
**
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
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** This file is part of the Qt Solutions component.
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** $QT_BEGIN_LICENSE:BSD$
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**
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** modification, are permitted provided that the following conditions are
** met:
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**     notice, this list of conditions and the following disclaimer.
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**     notice, this list of conditions and the following disclaimer in
**     the documentation and/or other materials provided with the
**     distribution.
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**     from this software without specific prior written permission.
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#include "qtlocalpeer.h"
#include <QCoreApplication>
#include <QDataStream>
#include <QTime>

#if defined(Q_OS_WIN)
#include <qt_windows.h>
#include <QLibrary>
typedef BOOL(WINAPI *PProcessIdToSessionId)(DWORD, DWORD *);
static PProcessIdToSessionId pProcessIdToSessionId = 0;
#endif
#if defined(Q_OS_UNIX)
#include <sys/types.h>
#include <time.h>
#include <unistd.h>
#endif

namespace QtLP_Private
{
#include "qtlockedfile.cpp"
#if defined(Q_OS_WIN)
#include "qtlockedfile_win.cpp"
#else
#include "qtlockedfile_unix.cpp"
#endif
}

const char *QtLocalPeer::ack = "ack";

QtLocalPeer::QtLocalPeer(QObject *parent, const QString &appId) : QObject(parent), id(appId)
{
  QString prefix = id;
  if (id.isEmpty())
  {
    id = QCoreApplication::applicationFilePath();
#if defined(Q_OS_WIN)
    id = id.toLower();
#endif
    prefix = id.section(QLatin1Char('/'), -1);
  }
  prefix.remove(QRegExp("[^a-zA-Z]"));
  prefix.truncate(6);

  QByteArray idc = id.toUtf8();
  quint16 idNum = qChecksum(idc.constData(), idc.size());
  socketName = QLatin1String("qtsingleapp-") + prefix + QLatin1Char('-') + QString::number(idNum, 16);

#if defined(Q_OS_WIN)
  if (!pProcessIdToSessionId)
  {
    QLibrary lib("kernel32");
    pProcessIdToSessionId = (PProcessIdToSessionId)lib.resolve("ProcessIdToSessionId");
  }
  if (pProcessIdToSessionId)
  {
    DWORD sessionId = 0;
    pProcessIdToSessionId(GetCurrentProcessId(), &sessionId);
    socketName += QLatin1Char('-') + QString::number(sessionId, 16);
  }
#else
  socketName += QLatin1Char('-') + QString::number(::getuid(), 16);
#endif

  server = new QLocalServer(this);
  QString lockName = QDir(QDir::tempPath()).absolutePath() + QLatin1Char('/') + socketName + QLatin1String("-lockfile");
  lockFile.setFileName(lockName);
  lockFile.open(QIODevice::ReadWrite);
}

bool QtLocalPeer::isClient()
{
  if (lockFile.isLocked())
    return false;

  if (!lockFile.lock(QtLP_Private::QtLockedFile::WriteLock, false))
    return true;

  bool res = server->listen(socketName);
#if defined(Q_OS_UNIX)
  // ### Workaround
  if (!res && server->serverError() == QAbstractSocket::AddressInUseError)
  {
    QFile::remove(QDir::cleanPath(QDir::tempPath()) + QLatin1Char('/') + socketName);
    res = server->listen(socketName);
  }
#endif
  if (!res)
    qWarning("QtSingleCoreApplication: listen on local socket failed, %s", qPrintable(server->errorString()));
  QObject::connect(server, SIGNAL(newConnection()), SLOT(receiveConnection()));
  return false;
}

bool QtLocalPeer::sendMessage(const QByteArray &message, int timeout)
{
  if (!isClient())
    return false;

  QLocalSocket socket;
  bool connOk = false;
  for (int i = 0; i < 2; i++)
  {
    // Try twice, in case the other instance is just starting up
    socket.connectToServer(socketName);
    connOk = socket.waitForConnected(timeout / 2);
    if (connOk || i)
      break;
    int ms = 250;
#if defined(Q_OS_WIN)
    Sleep(DWORD(ms));
#else
    struct timespec ts = {ms / 1000, (ms % 1000) * 1000 * 1000};
    nanosleep(&ts, nullptr);
#endif
  }
  if (!connOk)
    return false;

  QDataStream ds(&socket);
  ds.writeBytes(message.constData(), message.size());
  bool res = socket.waitForBytesWritten(timeout);
  if (res)
  {
    res &= socket.waitForReadyRead(timeout); // wait for ack
    if (res)
      res &= (socket.read(qstrlen(ack)) == ack);
  }
  return res;
}

void QtLocalPeer::receiveConnection()
{
  QLocalSocket *socket = server->nextPendingConnection();
  if (!socket)
    return;

  while (socket->bytesAvailable() < (int)sizeof(quint32))
    socket->waitForReadyRead();
  QDataStream ds(socket);
  QByteArray uMsg;
  quint32 remaining;
  ds >> remaining;
  uMsg.resize(remaining);
  int got = 0;
  char *uMsgBuf = uMsg.data();
  do
  {
    got = ds.readRawData(uMsgBuf, remaining);
    remaining -= got;
    uMsgBuf += got;
  } while (remaining && got >= 0 && socket->waitForReadyRead(2000));
  if (got < 0)
  {
    qWarning("QtLocalPeer: Message reception failed %s", socket->errorString().toLatin1().constData());
    delete socket;
    return;
  }
  socket->write(ack, qstrlen(ack));
  socket->waitForBytesWritten(1000);
  socket->waitForDisconnected(1000); // make sure client reads ack
  delete socket;
  emit messageReceived(uMsg); //### (might take a long time to return)
}
